WebAssembly

I have lamer questions:
1. Can I write an application with Directx?
2. Can I upload dll from the server?
3. Can I write any application in C ++?
4. Translated by translate.google.com:
Inside the browser-Usage cases- "NPAPI common users, as part of the Internet security model and the API."
What does it mean? Can I add the cut-out NPAPI support in the browser?
5. Does the code work only in the browser? And in any way it is impossible will address to Windows (for example to launch a file in it)?
6. Can I use encryption technology?


С уважением,
Аниме Любитель
anime_lubitel@mail.ru